Machine for manufacturing undercut sand molds



NOV. 29, 1938. JEUNE; 2,138,701

MACHINE FOR MANUFACTURING UNDERGUT SAND MOLDS Filed Aug. 5, 1936 2Sheets-Sheet l INVENTOR FRANK H. LeJEUNE A TTORNEYS Nov. 29, 1938; F. H.LE JEUNE MACHINE FOR MANUFACTURING UNDERCUT SAND MOLDS Filed Aug. 5,1936 2 Sheets-Sheet 2 FIG.5.

INVENTOR FRANK H. LEJEUNE ATTORNEYS Patented Nov. 29, 1938 UNITED STATESPATENT OFFIQE MACHINE FOR MANUFACTURING UNDER- CUT SAND MOLDSApplication August 3, 1936, Serial No. 94,084

1 Claim.

The invention relates to machines for forming undercut grooves in sandmolds and has for one of its objects the obtaining of a simpleconstruction of manually operable mechanism for accomplishing thispurpose. The invention has for another of its objects to provide animproved construction of combined presser and cutter head. To this endthe invention consists in the construction as hereinafter set forth.

In the drawings:

Figure 1 is a vertical central section through the machine; 1

Figure 2 is a plan view thereof;

Figure 3 is an end elevation;

Figure 4 is an enlarged View of a portion of Figure 2 showing theconstruction of the grooving mechanism;

Figures 5 and 6 are respectively a sectional end elevation and a frontelevation of Figure 4;

Figure 7 is a cross section on the line 1-1 of Figure 4.

The machine is more particularly designed for forming annular ribs oncylindrical castings as for instance brake drums or integral brake drumsand hubs for vehicle wheels. The molds for such castings are usuallyformed by patterns having draft in an axial direction and therefore anyextension of the mold cavity for forming surrounding ribs must beundercut. With my improved machine this undercutting is accomplished bythe relative rotation of an annular table on which the sand mold issupported and a head extending upward through the central opening insaid table into the mold cavity and radially adjustable with respect tothe axis of rotation. There is also provision for manually efiectingthis relative rotation and radial movement so that the operator mayquickly perfor the undercutting operation.

In detail, A is an annular supporting frame mounted upon legs B andprovided on its upper face with a circular race groove C for a series ofballs D. E is an annular table having a corresponding race groove E forengaging the balls D and also provided with a depending portion E havingrack or gear teeth E on its under face. The table E is further providedwith a detachable top plate F for receiving the mold to be operated uponand which is exchangeable to correspond to different sizes or shapes ofmolds. This plate is axially registered with the table E by means ofdowel pins F depending therefrom and engaging corresponding recesses inthe table. The plate F is further provided with upwardly projecting pinsF for engaging sockets in the flask G for the sand mold so as toproperly register the mold with the table.

Extending transversely of the annular frame A are parallel guide rods Hwhich are secured in position by suitable means such as the nuts Hengaging threaded end portions H? and the washers H which latter bearagainst the outer face of the member A. I is a carriage slidably mountedon the rods H within the annular frame A and extending upward toapproximately the level of the top face of the table E. I is a lugprojecting upward from the carriage I through the opening in the annularplate F, and J is a detachable head supported on the carriage andcentered by the lug I. This head J has projecting upward therefrom thespaced posts J to which are secured the opposite ends of a segmentalpresser member K. The major portion of the outer face of the member K isof a radius corresponding to the inner face of the cylindrical wall ofthe mold cavity so that when said member is adjusted radially with thecarriage I, it will bear or press against this face. However the endportions of the outer face are rounded to avoid scraping or cutting thesand. The member K is not, however, rigidly mounted on the carriage butis yieldably attached thereto by means of headed guide pins K having athreaded engagement therewith and slidably engaging bearings in theposts J. Springs L located in recesses in said posts above and below thepins K and also engaging registering recesses in the member K serve toyieldably press the latter radially outward to the limit permitted bythe headed pins. The member K is further provided with a series of slotsK which correspond in position to the location of the annular ribs whichare to be formed on the casting. Engaging these slots are cutter bladesM the shanks M of which extend radially inward and are rigidly mountedon the head J. In normal position the cutters M are withdrawn into theslots K If, however, the member K is held against radial outwardmovement during the continued movement of the carriage I, the cutterswill be projected from the slots so as to engage the sand of the mold.The arresting of the radial outward movement of the member K is effectedby a ring N surrounding the inner edge of the annular, plate F andprojecting upward therefrom. This ring has a beveled top face and themember K is provided with a correspondingly beveled lower face so thatwhen these faces engage each other further outward movement of themember K is arrested. However, relative rotary movement of the ring N inthe member K is permitted as will be hereinafter described. The lengthof the slots K is sufficient not only to receive the cutter blades M butto leave an opening in advance of the cutting edge thereof through whichthe sand may be carried inward into a vertical channel K through whichit can escape.

For the purpose of slicking the sand of the undercut or grooved portionsof the mold the cutter blades M are formed both to effect the cuttingand the shaking. As shown particularly in Figure 4, the portions M ofthe end or outer faces of the cutter blades are of a radii respectivelycorresponding to the faces of the completed undercuts or grooves.However, the forward portions M are of smaller radii and furthermore, asshown in Figures 5 and 6 in addition to Figure 4, the forward portionstaper forwardly both in radial and axial section. The front ends of theforward portions effect the cutting and the flaring parts of the forwardportions M in rear of the front end and also the portions M effect theslicking.

To provide for the fillets which are to be formed at the junctions ofthe annular ribs and the brake flange, the presser member K is providedin rear of and in peripheral alignment with the slots K with the beads Kshown particularly in Figures 4, 5, 6 and '7. These beads have theirforward ends tapered both radially and axially to freely enter theundercuts or grooves formed by the cutter blades. The portions of. thebeads in rear of the tapered portions however have a section especiallyin an axial direction to compact and slick the sand to round the cornersand thereby provide for the desired fillets.

To perform the work of cutting the grooves in the mold there must firstbe a rotation of the table. E with respect to the frame and carriage I,and

second a radially outward movement of the member K and cutter bladesM-due'to a sliding movement of the carriage I-on the guides H. Tomanually perform both of these movements the following mechanism isprovided. 0 is a shaft which is jou-rnaled in a bearing 0' in the frameA and projects radially outward therefrom. On his shaft is mounted agear wheel P which is in mesh with the annular or. gear teeth E on thetable. Adjacent to the gear wheel P'is a second gear wheel' Q which is.revoluble on the shaft 0 and which is in mesh with the complementarygear wheel R on a shaft S parallel to the shaft 0 and mounted in abearing S in the frame A. The outer ends of the shafts O and S areprovided with squared or polygonal portions '0 and S which correspond insize and are adapted to receive a corresponding socket T on a hand crankT. The inner end of this socket T is provided with clutch teeth Tadapted to engage with corresponding clutch teeth Q on the gear wheel Q,the arrangement being such that when the crank T is engaged with theshaft 0 it may either rotate this shaft alone or by moving the clutchteeth T and Q into engagement will simultaneously rotate the gear wheelQ. The shaft S has an inward extension S which is threaded to engage anut U in the carriage I. 'Ihis'will cause a movement of the carriage onthe guidesH whenever the shaft S is revolved either by direct engagementtherewith of the hand crank T or through the medium of the gear wheels Qand R. and the clutch engagement between the hand crank T when mountedon the shaft 0. On the other hand, when the crank T is engaged with theshaft 0- but has its clutch teeth 'I out of engagement with the clutchteeth Q, then the shaft 0 alone will be revolved, which through the gearwheel P will communicate rotary motion to the table E.

With the construction as described, the operation is as follows: Thesand mold is first formed in the flask G in the usual manner and. thisflask is then placed upon the plate F and is registered in axialalignment with the table E by means of the pins F This will alsoregister the ring N with the inner face of the mold cavity. During theplacing of the mold upon the plate F and table E the carriage I is inthe position where the member K and cutters M are withdrawn radiallyinward so as to be wholly within the mold cavity and not to interferewith the sand walls After the flask is properly mounted the operatorplaces the hand crank T in engagement with the squared portion 0 of theshaft 0 and pushes it inward far enough to engage the clutch teeth Twith the corresponding clutch teeth Q. The shaft is then rotated by thecrank which will simultaneously revolve the table E together with themold supported thereon and will move the carriage I radially outward onthe guides 1-1. This will carry the presser member K outward until itslower beveled edgecomes in contact with the upperbeveled face of thering N at which time the outer face of the member K will be in contactwith and press against the inner cylindrical face of the mold andthereby prevent damage-to this face as well-as slick the same. Furtheroutward movement of the member K is then prevented but the continuedmovement of the carriage will project the blades M from the recesses Kthereby shaving away the sand which is carried inward through the slotand dropped through the channel K The blades also compact and slick thesand of the undercuts or grooves. In addition, the beads of the pressermember compact and slick the sand at the corners of the undercuts orgrooves to provide for the fillets in the casting. During this continuedmovement, the springs L are compressed. Outward movement .of the bladesM is also limited, preferably by a stop formed by a rod V projecting'rearward from the carriage I parallel to its direction 'of movement.This rod'extends through a bearing W on the frame A and has a threadedend portion for engaging lo'cknuts X. Thus by adjusting these nuts theoutward movement of the carriage I may be limited asdesired. When thislimit is reached the table E may still be revolved by the crank Tprovided that the clutch teeth T are disengaged from the clutch teeth Q.To withdraw the cutters and presser member K from engagement with themold, the crank T is transferred into engagement with the shaft S, andby then rotating the crank in the same direction this will impart areverse "rotation to the screw S from that transmitted from the shaft 0:and this turn will move the carriage radially inward. During thewithdrawal, the presser member K remains in engagement with the sandduring the withdrawal of the cutters and then. is withdrawn.

What I claim as my invention is:

In a machine for'undercutt'ing sand molds, the. combination with "apresser member engageable with the wall of :a mold cavity, of a combinedcutter-and slick adapted to extend. beyond said presser member :andhaving at its front end a solid cutting portion :and in rear of saidcutting portion :a slicking portion for the entire surface

